For communications there exists a variety of access technologies and more access technologies are being developed to meet ever-increasing demand for capacity and requirements on maximum response times, time jitter etc. Particularly, for radio communications different technologies such as GPRS (General Packet Radio Services) UMTS (Universal Telecommunications Systems) and WLAN (Wireless Local Area Network) it is known to transmit packet data over one of a plurality of available networks.
A network operating according to only one access technology we call a homogeneous network. A network including different access technologies we call a heterogeneous network.
X. G. Wang, J. Mellor and K. Al-Begain, ‘Towards Providing QoS for Integrated Cellular and WLAN Networks,’ PostGraduate Networking Conference (PGNet2003), Liverpool, UK, June 2003, describes interconnecting WLAN radio access network with 3G or 2G cellular network as an efficient way to enhance network operator service. The publication discusses two different methods for merging WLAN and cellular networks, loose coupling and tight coupling. For the loose coupling WLAN and cellular networks are two separate access networks, with connected core networks. For the tight coupling they suggest WLAN to be employed as a new radio access technology within the cellular system. Regardless of the access technology, for tight coupling there would only be one common cellular core network. According to the prior art QoS model structure, a CAC (Connection Admission Control) Module admits the number of flows that can be served and allocates bandwidth to the flows through signaling to all the network nodes along the traffic path. It also needs to maintain the QoS requirements of existing connections. CAC uses some reservation protocols, e.g. RSVP, to book the actual resource for users' flow. The publication suggests a user-triggered handover when roaming from cellular networks into WLAN and a normal handover when roaming from WLAN into cellular networks.
X. G. Wang, G. Min, J. Mellor, K. Al-Begain, L. Guan, ‘An adaptive QoS management scheme for interworking cellular and WLAN networks,’ 7th UK Simulation Society Conference (UKSim2004), Oxford, UK, Mar. 29-31, 2004, pp. 145-150, addresses various challenges generated by designing an integrated WLAN and 3G network and presents simulation experiments and results concerning resource utilization, call blocking probability and handoff dropping probability.
Ken Murray, Dirk Pesch: ‘State of the Art: Admission Control and Mobility Management in Heterogeneous Wireless Networks,’ TSSG, Waterford Institute of Technology Cork Rd, Waterford, Ireland, May 2003, discusses seamless intersystem roaming across heterogeneous networks. The motivation for heterogeneous networks arises from the fact that no one technology or service can provide ubiquitous coverage and continuous high QoS (Quality of Service) levels across multiple spaces. It will therefore be necessary for a mobile terminal to employ various points of attachment to maintain connectivity to a corresponding node at all times. Both packet and circuit switched services can be freely mixed, with variable bandwidth and delivered simultaneously to the same user with specific quality level. Satellite networks promise global coverage and total ubiquitous computing but with lower QoS constraints than its cellular counterparts, while WLAN provides high-speed data service (up to 11 Mb/s with 802.11b and 54 Mb/s with 802.11a/g) over a geographically small area. The technologies differ in bandwidth, latency, power consumption and cost. Admission control and mobility management strategies facilitate load balancing between access networks. Users can be forced to handover to another network to make way for users with more demanding bandwidth requirements and can thus prioritize users. It may be possible using an admission control algorithm to admit a user to multiple networks simultaneously and use multiple connections to deliver services to the user and thus achieve a higher QoS than that offered from a single network. If multiple networks are available to a user at any one time, then choosing the most optimal network for a particular service delivery and choosing the correct time to execute a vertical handover to improve the QoS for all users are important factors. The publication describes Fuzzy Logic concepts for handover initiation, network selection and handover execution. The document concludes that admission control schemes across heterogeneous networks based on radio channel characteristics, resource availability, QoS constraints and user policy still remains an open issue.
C. A. Mantilla, J. L. Marzo, ‘A QoS Framework for Heterogeneous Wireless Networks using a Multiagent System,’ European Wireless 2004, The Fifth European Wireless Conference Mobile and Wireless Systems beyond 3G, February, 2004, describes QoS in heterogeneous wireless network, multiagent systems and a QoS Framework in heterogeneous wireless networks using a multiagent system. The document proposes a multiagent system, where each access point in each technology or network has a group of agents with different roles, cooperating or competing. The global functions of the MAS (MultiAgent System) include call admission control to accept or to reject an incoming call, registration of the call with the security policies, resource allocation QoS parameters mapping with a new network and execution of handover. A radio resource manager agent is responsible of the status of the access point, the available resources and the execution of horizontal handover, or handover within a technology, and vertical handover, or handover between access technologies.
E. Mohyeldin, M. Dilinger, E. Schulz and J. Luo, ‘Joint admission control and scheduling algorithm in tightly coupled heterogeneous networks,’ 6th WWRF Meeting in London, England, June 2002, presents two-stage Admission Control and Resource Scheduling for tightly coupled sub-networks (UMTS and WLAN). A radio network controller, RNC, owns and controls the radio resources of all the sub-networks in its domain, where the interworking between sub-networks mostly goes through the RNC. Incoming traffic inside of the systems is divided into different traffic types after a first stage of Joint Session Admission Control, JOSAC. A second stage of Session Admission Control, SAC, selects the transmission physical mode of bearer service or drop the application in case the network cannot provide the requested service. Based on the chosen static service and network profile in the first stage, the first stage of the admission control assigns a certain range for the weights defined for the service types based on the network, terminal and user profiles, which are offered to the second stage. The tightly coupled traffic stream over two RATs (Radio Access Technologies) is scheduled by JOSCH (Joint Radio Resource Scheduling), working between the first and second stage. The split traffic after JOSCH is forwarded to individual SAC in each RAT defined sub-network with delay bounds. SAC maps the split traffic, with offered control information from JOSCH, into conventional traffic type with a concrete priority weight. The QoS class dimension of the scheduling allocates resources for different QoS classes. The joint admission control assigns radio resource to the corresponding amount of traffic in each sub-network according to the load of the sub-network, the expected traffic model and the feasibility of traffic splitting.
J. Luo, E. Mohyeldin, N. Motte, M. Dilinger, ‘Performance Investigations of ARMH in a Reconfigurable Environment’ SCOUT Workshop, September, 2003, discusses the ARMH (Adaptive Radio Multi Homing) concept for tightly coupled radio access technologies, RATs, and investigates simultaneous connections in individual radio networks with the support of multiple radio addresses belonging to terminals. For joint admission control, the traffic cannot be split; the session/messages cannot be split over different networks, but can be admitted alternatively to a different one for packet switched communications. JOSAC can only give a gain due to traffic routing, or alternatively, traffic diversion to a different system. The JOSCH offers the detailed traffic splitting.
In case a mobile terminal has simultaneous connections supported by reconfigurable terminals, data flows and control commands can be routed via different air interfaces, which have different delay characteristics in terms of average delay and delay variance (jitter). The traffic split is motivated by a reduced load over individual networks, thereby providing higher trunking gain as seen by radio resource management, RRM, and better QoS as seen by a user if traffic splitting is designed according to user profile and demands, and network architecture.
The document mentions an example, a terminal demanding a scalable video service from a remote server through tight coupled sub-networks (UMTS and WLAN). Both networks assumed to be controlled by a common RNC. In order to establish simultaneous sub-streams belonging to the same video context, RNC first receives an application or a request from a mobile terminal with multiple radio accesses/addresses. The RNC applies to or urges a remote server for traffic splitting, indicating average rate in each sub-link. Traffic is split and sent to the RNC, which receives the split traffic and maps it to the tightly coupled sub-networks. The split traffic comprises labeled (for each sub-network) and time-indexed packets. A synchronization mechanism in RNC remedies delays generated by the radio sub-networks.
International Patent Application WO03088686 reveals a method of multi-service allocation in multi-access systems. Users of a given service in a wireless communication system that includes a plurality of multi-service sub-systems are allocated to one of the sub-systems in accordance with a combined capacity region of the wireless communication system. The combined capacity region is determined based upon capacity regions of each of the plurality of multi-service sub-systems, which capacity regions are determined using a relative decrease in users of a first service as a function of an increase in users of a second service.
None of the cited documents above discloses admission control for multi-technology access, the admission control serving one or more sessions, each received by a multi-technology access system in one data flow, over more than one access technology at the same time by dividing a session over available access technologies, the dividing being performed within the access system, or by splitting individual data flows over more than one access technology. Furthermore, none of the cited documents reveals access technology data-flow selection based on data security, or user or terminal preferences.